Blackcurrants have already earned a reputation amongst the healthiest fruits thanks to a high antioxidant content. But in New Zealand, where five per cent for the world's crop is grown, researchers have been investigating ways to make them even better.
Karl Crawford, business leader for food and health at HortResearch, told NutraIngredients.com that New Zealand has had a programme for breeding blackcurrant varieties suited to the country's climate for several years.
But now the crown research institute is focusing more sharply on health. Its latest cultivar, "Blackadder", was bred for its colour and vitamin C content, which effects the antioxidant level of the fruit and hence other functional areas.
The researchers are also looking at ways to conserve the anthocyanins "the main antioxidants" during processing.
Crawford explained that the researchers measure the anthocyanins using high pressure liquid chromatography (HPLC) and look at the variation in the four main types of anthocyanins, as well as total anthocyanin content.
Studies so far have shown that total anthocyanin content in the blackcurrant gene pool can vary by as much as eight times from the lowest to the highest.
"The cultivars currently on the market fall somewhere in the middle of the range," said Crawford.
"We are looking at the different profiles and amounts of anthocyanins and relating this to antioxidant ability and ultimately to health. The idea is to produce a new cultivar where we can substantiate health claims."
Moreover the studies shed some light on potential health benefits of processed products, and how the juice from different cultivars can be blended to obtain the desired benefit.
A keen area of interest for all of this is in exploiting blackcurrants' anti-ageing potential, including cognitive function.
A recent in vitro study published on-line in the Journal of the Science of Food and Agriculture (doi: 10.1002/jsfa.2409) tested the effect of blackcurrant extracts against oxidative stress from hydrogen peroxide on human brain cancer cell cultures (SH-SY5Y neuroblaster cells and HL-60 cells), and found that the cells were completely protected.
Although the mechanism of Alzheimer's is not clear, more support is gathering for the build-up of plaque from amyloid deposits. The deposits are associated with an increase in brain cell damage and death from oxidative stress.
If replicated in vivo, this finding lends hope to the possibility that blackcurrants could prevent the onset of Alzheimer's disease. This, in turn, gives weight to their use in a range of processed functional foods.
Other health aspects HortResearch is bearing in mind for future cultivars are eye, joint and skin health.
Crawford described the research as "an ongoing iterative process".
"What we learn about the health properties of blackcurrants is fed back into the breeding programme," he said.
It seems that black currants respond particularly well to New Zealand's particular climate.
"There has been some work looking at the anthocyanin content of NZ sourced product versus other sources that has shown higher levels for the NZ fruit," said Crawford. "It may be that the intense natural light in New Zealand in the absence of scattering by air pollution may play a role, together with variety sections suited for local climatic and soil conditions."
The researchers are also looking at other factors, including consistently high fruit yields, pest and disease resistance (especially gall mite) under New Zealand conditions when grown on a large-scale commercial basis, a seasonal spread from early December through to late January, and low chill requirement.
Enhanced juice characteristics, such as better colour and flavour, are important too, and may help expand blackcurrants' use in food products - mainstream as well as functional.
The programme is based at HortResearch in Canterbury and is supported by funding from the New Zealand Foundation for Research, Science and Technology and Blackcurrants New Zealand Ltd.
Ian Turk, chief executive of Blackcurrants New Zealand, told NutraIngredients.com that this year's blackcurrant harvest has just come in and is thought to be around 8000 tonnes. Over 90 per cent of which will be exported; the major world market is Europe.
There are a number of processors are based in New Zealand, including Tasman Extracts and Just the Berries, which cater to the nutraceutical market.